The invention relates to a diaphragm pump driven by a swash ring and including the following features: a drive shaft having an axis; a ball bearing having an axis, said ball bearing including inner and outer races; a hub-like bearing member mounting said inner race to said shaft so that the axis of said shaft and the axis of said ball bearing intersect at a small angle at a first point spaced apart from said ball bearing; a tightly clamped diaphragm; and a wobble finger operationally connecting said outer race and said diaphragm, said wobble finger including a screw which has an axis that penetrates said diaphragm at a second point that moves along a path having a center position, with said second point at said center position lying in a plane that is perpendicular to the axis of said shaft and that passes through said first point.
In a commercially available diaphragm pump manufactured by an American firm and including these features, a plate-shaped connecting member is provided which has a circular cutout by which it is pressed in a force fit onto the outer ball bearing race. Two wobble fingers are screwed into the connecting member.
If ball bearings are to run satisfactorily for long periods of time, it is necessary for the journal fitting into the inner race as well as the bearing cage fitting over the outer race to fit very precisely. If, for example, the diameter of the journal is too large, the inner race expands' and too small a diameter of the bearing cage, which then compresses the outer race, has a particularly run inhibiting effect. The assurance of close diameter tolerances constitutes a considerable cost factor in the manufacture of the known connecting member. Moreover, this annular connecting member must have a sufficiently large ring cross section in order to be able to absorb the tangential forces that are generated. Therefore it becomes relatively heavy and causes the diaphragm pump to vibrate considerably.